This application claims the priority of Japanese Patent Application No. 10-359390 filed on Dec. 17, 1998, which is incorporated herein by reference.
The present invention relates to a cosmetic composition and, in particular, to an improvement of a thickener to be compounded therein.
Various aqueous thickeners are compounded into the cosmetic so as to preserve the form of cosmetic. Examples of organic compound thickeners include natural polymers such as polysaccharides, casein and xanthan gum, and synthetic polymers such as acrylic polymer and carboxyvinyl polymer. Examples of inorganic compound thickeners include various clay minerals such as montmorillonite, and silica and the like. These thickeners have been suitably and selectively used according to its purposes and effects.
In case of using a composition including such thickeners for the cosmetic, stable viscosity i.e., pharmaceutical form can be preserved within various temperature ranges, is required, while the feel in using, i.e., usability and the like are required because the cosmetic is mainly used to the skin as external use.
However, among the cosmetic compositions, which include the conventional thickeners, the composition that sufficiently satisfies stability of viscosity and favorable usability is unknown.
For example, the cosmetic compositions compounding conventional polymer thickeners such as vinyl thickeners and cellulose thickeners, which have been used in the past, are comparatively high in stability and require a small amount of thickener. However, in the case where such composition is used to the skin, sliminess feeling peculiar to polymer is occurred and the composition has unfavorable feeling of use. Also, the cosmetic composition comprising clay mineral has high thixotropic property and refreshing feeling after use, and is favorable in usability. However, such composition is unstable because syneresis occurs easily due to temperature change.
The present invention is achieved in view of the foregoing prior art, an object of the present invention is to provide a cosmetic composition which is excellent both in stability of viscosity and in usability.
As the result of diligent studies of the present inventors for attaining the above-mentioned object, it has been found that a cosmetic composition, which is excellent both in stability of viscosity and in favorable usability, can be obtained by compounding a specific associative thickener as a main ingredient of thickeners. Further, the present inventors have been found that time stability of viscosity at high temperature and time stability of emulsion in case of an oil-in-water emulsion composition, are improved by using a water-soluble polymer or a polyhydric and monohydric lower alcohols together with the associative thickener. Accordingly the present invention has been accomplished.
Namely, a cosmetic composition of the present invention comprises an associative thickener, which is composed of a compound shown in Formula (1),
R1xe2x80x94{(Oxe2x80x94R2)kxe2x80x94OCONHxe2x80x94R3[xe2x80x94NHCOOxe2x80x94(R4xe2x80x94O)nxe2x80x94R5]h}mxe2x80x83xe2x80x83(1)
wherein R1, R2, and R4 each is a hydrocarbon group, which may be same or different each other; R3 is a hydrocarbon group, which may have urethane bond; R5 is a straight chain, branched chain or secondary hydrocarbon group; m is an integer of 2 or more; h is an integer of 1 or more; and k and n each is an integer within the range of 0 to 1000, respectively.
Also, in the present invention, it is preferable that the associative thickener is an alkylene group having 2-4 carbon atoms that R2 and/or R4 each may be same or different or phenylethylene group.
It is also preferable that R3 is a residue of polyisocyanate which is shown as R3xe2x80x94(NCO)h+1.
It is also preferable that the polyisocyanate which is shown as R3xe2x80x94(NCO)h+1 is a polyisocyanate having urethane bond, which is obtained by reacting divalent to octavalent polyol with divalent to tetravalent polyisocyanate.
It is also preferable that R1is a residue of polyol which is shown as R1xe2x80x94(OH)m.
It is also preferable that RW5 is a straight chain, branched chain or secondary hydrocarbon group having 8-36 carbon atoms.
It is also preferable that the associative thickener is a resultant of one or more of polyetherpolyol that is shown as R1xe2x80x94[(Oxe2x80x94R2)kxe2x80x94OH]m, one or more of polyisocyanate that R3 is shown as Rxe2x80x943 (NCO)h+1, and one or more of polyether monoalcohol shown as HOxe2x80x94(R4xe2x80x94O)nxe2x80x94R5.
It is also preferable that the cosmetic composition of the present invention comprises 0.01 to 10 wt % of the associative thickener.
It is also preferable that the cosmetic composition of the present invention further comprises a water-soluble polymer.
It is also preferable that viscosity ratio of water-soluble polymer/associative thickener is 0.01 to 100.
It is also preferable that the cosmetic composition of the present invention further comprises a polyhydric lower alcohol.
It is also preferable that the cosmetic composition of the present invention comprises 0.01 to 10 wt % of the associative thickener and 0.1 to 30 wt % of the polyhydric lower alcohol.
It is also preferable that the cosmetic composition of the present invention further comprises a monohydric lower alcohol.
It is also preferable that the cosmetic composition of the present invention comprises 0.01 to 10 wt % of the associative thickener and 0.1 to 30 wt % of the monohydric lower alcohol.
It is also preferable that the cosmetic composition of the present invention is an oil-in-water emulsion composition.
It is also preferable that the cosmetic composition of the present invention comprises 0.1 to 5 wt % of the associative thickener, 40 wt % or less of an oily ingredient, and 10 times or less of cmc (critical micellar concentration) of an ionic surfactant.
It is also preferable that the cosmetic composition of the present invention comprises 0.1 to 5 wt % of the associative thickener, 40 wt % or less of the oily ingredient, and 10 wt % or less of a nonionic surfactant whose HLB is 12 or less.
It is also preferable that the cosmetic composition of the present invention comprises 0.1 to 5 wt % of the associative thickener, 40 wt % or less of the oily ingredient, and 8 wt % or less of the nonionic surfactant whose ELB is 15 or less.
It is also preferable that the cosmetic composition of the present invention comprises 0.1 to 5 wt % of the associative thickener, 40 wt % or less of the oily ingredient, and 6 wt % or less of the nonionic surfactant whose HLB is 15 or more.